NO! Don’t use fake marble and two different sizes of fake on top of fake marble. And don’t use real marble either.
Pick one tile, in one color, and use an interesting shape. Something that matches your wall paint would work.
https://www.homedepot.com/p/Ivy-Hill-Tile-Vintage-Florid-Lantern-Light-Blue-6-1-4-in-x-7-1-4-in-x-10-mm-Ceramic-Wall-Mosaic-Tile-30-pieces-4-8-sq-ft-Box-VINTAGEFLORIDLANLTBLU/206496938
Q